This invention relates to a filter for an air-conditioning or heating system for a motor vehicle, having a filter body made of a material arranged in several layers with open pores which are coated with a granular adsorption agent, particularly activated-carbon granules.
In the case of a known filter of the initially mentioned type (German Patent Document DE-U 87 17 296.8), the filter body, which is formed of three layers, is placed in a frame.
In the case of another construction of a multi-layer filter (European Patent Document EO-A 0 162 922), it is provided that the filter elements are arranged in a housing made of cardboard or plastic which is arranged in an air duct or the like with the insertion of an elastic sealing material.
It is also known (German Patent Document DE-C 34 41 918) to provide a plate-shaped filter insert with a frame which has an improved sealing to a filter housing. For this purpose, the frame is surrounded by an edge bordering made of a foamed elastic plastic material which reaches around the filter insert in the edge area. The plastic material, which foams during the manufacturing process, assumes the desired shape into the area of the web-shaped filter cloth.
It is also known (German Patent Document DE-A 38 39 352) to mold a frame to the multi-layer filter body in such a manner that the material of the edge penetrates into the edge of the filter body down to a predetermined depth. This results in a very good sealing with respect to the frame so that a filter is created which is used as an odor filter and which is suitable for an air-conditioning system of motor vehicles.
It is an object of the invention to improve a filter of the initially mentioned type.
This object is achieved in that the filter body, at least on its air outlet side, is covered by an air-permeable textile flat shaped structure in which the distances between the yarns are smaller than the outer dimensions of the granular adsorption agent.
The textile flat shaped structure, which may be a woven or knitted fabric, on the one hand, has the result that the multi-layered filter body is further stabilized while, on the other hand, the important advantage is obtained that this textile flat shaped structure retains adsorption agent which may possibly separate from the multi-layered filter body because of vibrations or the like. As a result, it is avoided that this granular adsorption agent, particularly activated-carbon granules, can reach the vehicle interior and cause dirt there and/or otherwise annoy the vehicle occupants.
In a further development of the invention, it is provided that the textile flat shaped structure surrounds the filter body in the manner of a stocking. This ensures that any adsorption agent is held back inside the filter while the textile flat shaped structure at the same time holds the whole filter body together so that it exists as a preformed constructional unit.
In a further development of the invention, it is provided that the edges of the textile flat shaped structure are shaped into a frame molded onto the filter body.
In another embodiment, it is provided that the edges of the filter body, together with the textile flat shaped structure, are clamped into a frame or shaft which is preferably formed by a housing. During this clamping-in, the edges of the filter body are pressed together so that here also a secure sealing is obtained which has the result that the filter may be used as a large-sized filter.
In a further development of the invention, it is provided that the reinforcing mesh is manufactured from a plastically deformable material, particularly metal. As a result, it is possible to adapt the filter body made of several layers of filter material and the reinforcing mesh to given spatial conditions by means of a plastic deformation.
In a further development of the invention, it is provided that the reinforcing mesh is arranged in parallel to the layers and is provided with spikes penetrating into at least the connecting layers. The reinforcing mesh with the spikes and the additional covering with the woven or knitted fabric has the result that the filter body has a relatively high rigidity so that it can be handled in a simple manner and mainly also without any danger of damage and/or any danger of a shifting of the layers with respect to one another.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.